Fossil Friday: The Complex Wing Folding of Earwigs
Today’s featured fossil, an earwig, is the paratype specimen of Cratoborellia gorbi, which I found and photographed at a German trader’s collection in July 2006, where I also discovered the holotype that is deposited in the collection of the Stuttgart Natural History Museum and was described by my fellow student Fabian Haas (Haas 2007). The fossil belongs to the living earwig family Anisolabididae and is three-dimensionally preserved as iron oxide-hydroxide (Goethite) in the Lower Cretaceous (115 million years old) laminated limestone of the Crato Formation from northeast Brazil. It is one of the very few fossil earwig specimens with spread hind wing, and documents a very similar pattern of wing folding to its living relatives.
Lay people may hardly be aware that many earwigs indeed have wings and can fly, as they only rarely do. However, they not only do possess wings, but also have very sophisticated adaptations in their construction. Just like beetles, they have hard forewings that serve as protective flaps (elytrae), while the hind wings fold in a complex way beneath the forewings (they even use their pincers to assist in the folding of the wings).
Another Example of Convergence
This is another example of striking convergence in the animal kingdom. These convergent adaptations can be traced back to the earliest known putative stem earwigs (Protelytroptera) from the Permian period about 299-252 million years ago (Haas & Kukalová-Peck 2001, Bethoux et al. 2016). Earwig wings not only fold like a fan in longitudinal direction, but additionally along a row of flexible patches in a transverse direction (Haas et al. 2000). This kind of natural origami is stunning and beautifully illustrated in a YouTube video by the ETH Zurich University (below), where researchers copied this design principle for biomimetic technology that could be used for foldable solar sails in space.
This highly complex mode of wing folding is one of the many examples of engineering marvels in insects that strongly suggest intelligent design as superior explanation to blind evolution.
- Bethoux O, Llamosi A & Toussaint S 2016. Reinvestigation of Protelytron permianum (Insecta; Early Permian; USA) as an example for applying reflectance transformation imaging to insect imprint fossils. Fossil Record 20, 1–7. DOI: https://doi.org/10.5194/fr-20-1-2016.
- Haas F 2007. Dermaptera: earwigs. Chapter 11.6, pp. 222–234 in: Martill DM, Bechly G & Loveridge RF (eds). The Crato Fossil Beds of Brazil. Cambridge University Press, Cambridge (UK), xvi+625 pp.
- Haas F, Gorb SN & Wootton RJ 2000. Elastic joints in dermapteran hind wings: materials and wing folding. Arthropod Structure and Development 29(2), 137–146. DOI: https://doi.org/10.1016/S1467-8039(00)00025-6.
- Haas F & Kukalová-Peck J 2001. Dermaptera hindwing structure and folding, new evidence for superordinal relationship within Neoptera (Insecta). European Journal of Entomology98(4), 445–509. DOI: https://doi.org/10.14411/eje.2001.065.